The present invention relates to a read/write integrated circuit, and more particularly to technology effectively utilizable for producing a composite head using, for example, a MR (magneto-resistance effect element) head as a read head, and an inductive head as a write head.
FIG. 13 shows a circuit that the present inventors studied prior to the present invention. This circuit comprises a pair of pnp type transistors QP1, QP2 as a pair on the upper side, and npn type transistors Q3, Q4 as a pair on the lower side. An input signal WD which is a low-level signal is used to turn on the transistors QP1, Q4, so that current is caused to flow from a first connection to a second connection. The first connection is a point at which the collector of the transistor QP1 and one end of a magnetic head L are coupled together, whereas the second connection is a point at which the collector of the transistor Q4 and the other end of magnetic head L are coupled together. When an input signal WDN is a low-level signal, the transistors QP2, Q3 turn on, so that current is caused to flow into the magnetic head L from the second connection to the first connection, that is, in the direction opposite to the preceding case.
An example of a current-control type magnetic head driving circuit is given in ISSCC "94 SESSION 17/DISK-DRIVE ELECTRONICS/PAPER FA17.multidot.6, PP 286.about.287.